Optimization of Bacillus thuringiensis Growth Conditions for Enhanced Larvicidal Activity against Anopheles mosquitoes larvae

One of the conventional ways of tackling malaria is the application of insecticides to mosquito breeding places. The study’s potential contributions to knowledge include providing a comprehensive understanding of how to maximize the effectiveness of Bti extracts, which can be applied in various ecological contexts and potentially lead to more effective mosquito control strategies. This study bridges the gap in identifying the optimal growth conditions for Bacillus thuringiensis to enhance its larvicidal activity against Anopheles mosquitoes larvae. This study aimed at enhancing the potential of Bacillus thuringiensis in the control of mosquito larvae. Bacillus thuringensis was isolated from soil samples in Katsina metropolis. Optimization of the culture conditions for the growth of the bacterium was carried out using selected parameters (pH, temperature, salinity and inoculum volume ) based on single factor at a time analyses. Mosquito larvae were obtained from Kofar Marusa water outlet, Katsina and characterized based on morphological and larvicidal stages (instar). The larvae mortality test was carried out using the prepared inocula of B. thuringensis, and the mortality rate among the larvae was recorded at intervals. The results obtained indicate that the population range of Bacillus thuringiensis ranged from 2.01 × 103 ± 0.03 CFU/mL to 3.62 × 103 ± 0.02 CFU/mL. The highest and lowest percentage mortality obtained were 85% and 50% respectively. The initial culture conditions used involved a temperature of 29 0C, a pH of 7.5, a salinity of 2% and inoculum volume of 1% v/v. The optimum conditions achieved involved a temperature of 30 0C, pH value of 7.5, salinity of 0% w/v and inoculum volume of 20% v/v. This indicates that B. thuringiensis represents an effective alternative to chemical insecticides in the control of mosquito larvae. Considering the fact that Bt toxins are safe for non-target species and human health, and so far, no resistance among the target has been detected, coupled with their specificity and eco-friendly nature, this study recommends using integrated pest management campaigns involving the use of bioinsecticides to serve as a better alternative to chemical insecticides which are harmful to the ecosystem.